Li₄Ti₅O₁₂ Coating on Copper Foil as Ion Redistributor Layer for Stable Lithium Metal Anode

Lithium metal is regarded as the most promising electrode material for the next generation of energy storage devices. However, low coulombic efficiency and short cycle lifespan caused by the unstable electrode interface have hindered its practical application. Constructing artificial coatings on the anode is one of the most effective approaches for remedying this, but the practical effects are still limited due to their poor regulation of Li⁺ ions transport and complex construction engineering. Herein, an “inverse concentration gradient” concept is put forward to improve the lithium metal anode, especially at high current density. A Li₄Ti₅O₁₂ artificial coating layer is fabricated on copper foil by a simple droplet coating method and a concentrated Li⁺ ions region near the electrode interface in the coating layer is formed in situ after the initial activation process, which alleviates the effects of space charge regions generated by ion depletion on the growth of lithium dendrites. Coupled with high ionic conductivity and “zero strain” characteristics, stable dendrite-free cycling of lithium metal anodes is achieved even at 5 mA cm⁻² in Li/Cu half cell. The unique concentration gradient design provides a new perspective for the interface regulation of advanced lithium metal anodes.